Adult female starlings (Sturnus vulgaris) were injected with testosterone in order to determine the song structures they had in memory. Those females had been caught in the wild in different geographical areas and had different ages. This hormone treatment clearly stimulated singing behaviour of females in isolation and revealed their ability to sing quite complex songs. Both categories of songs observed in males (warbling and whistles) were demonstrated and large repertoires were observed. Although the testosterone treatment may have altered the female song system and induced male-like vocalizations, it is interesting that none of the species-typic elements of male starlings was produced by the experimental females. Large changes were found in both repertoire size and composition over a year, revealing a high plasticity, even in older birds. We also found evidence that even under testosterone treatment, females do not necessarily sing all the songs they may have in memory.